1. Field of the Invention
The present invention relates to a coating instrument which is used in coating a coating solution on the surface of a member to be coated such as a sheet-like member or a panel-like member.
2. Description of the Related Art
Conventionally, as a coating instrument attached to a coating apparatus for coating a coating solution thinly and uniformly on the surface of a sheet-like member or a panel-like member to form a film layer, there is proposed, for example, that which is provided with a coating head constituted with a pair of head members in which between mutually opposing inner faces of the pair of head members, a pocket to which the coating solution is supplied and a groove-like slot which extends from the pocket to the leading edge of the coating head to open at the leading edge thereof are formed.
In the above-described coating instrument, the coating head is arranged in such a manner that the coating head opposes the sheet-like member (a member to be coated) and also that the longitudinal direction of the coating head is in alignment with the width direction of the sheet-like member, thereby coating the coating solution on the sheet-like member to form a film. Alternatively, the coating head is arranged above the panel-like member (a member to be coated), with the leading edge thereof pointed below, then, while the coating head is brought into contact with the panel-like member, the coating head is allowed to move, thereby coating the coating solution on the panel-like member to form a film.
Coating solutions to be coated by using a coating instrument equipped with the above-described coating head include a color paste for liquid crystal display and a resist agent for color filters. In this instance, uniform coating of a coating solution during coating work is important in terms of stable film formation on a sheet-like member or a panel-like member, which necessitates an accurate adjustment of the width of a slot of the coating head.
In this respect, Japanese Published Unexamined Patent Application No. 9-131561 and Japanese Patent No. 3501159 have proposed coating instruments equipped with an adjuster for adjusting the width of a slot. In these coating instruments, the width of the slot is adjusted in advance by the adjuster, thereby a coating solution is coated stably.
Meanwhile, in conventional coating instruments, there is a case where, even if the width of a slot is set to be a predetermined value at the time of initial use, the slot varies in width with the lapse of time, resulting in an inability to coat a coating solution stably. In this instance, in order to return the width of the slot to the predetermined value, it is necessary to interrupt coating work temporarily for readjustment of the width of the slot. This poses a problem in that the work is greatly reduced in efficiency.
In view of the above situation, a coating instrument capable of automatically controlling the width of a slot is strongly desired. However, this coating instrument is unable to continuously measure the width of the slot during coating work. Thus, no information is available about variation in the width of the slot, thus making it very difficult to automatically control the width of the slot.
The present invention has been made in view of the above situation, an object of which is to provide a coating instrument capable of automatically controlling the width of a slot.